SVIDEO MOD for Hitachi CPT 1420R
Hitachi CPT-1420R is a PAL-N/M & NTSC 14" TV set that has RF and composite video input.
From CPT-1420R Schematics we can see that this set uses Sanyo LA7680 Signal Processor IC. Chroma In (pin 40) gets filtered signal from Composite Video IN + Color Control, passing through C503 decoupling capacitor (0.01uF):
To inject Chroma signal from S-Video we can remove C503 capacitor, and add a SPDT toggle switch that would allow you to switch from S-Video Chroma Input to Chroma signal filtered out from Video IN (point B). Luma signal can be connected straight to Video IN. The circuit would look like this:
I also added a 75 ohms resistor from Chroma to GND as suggested in Datasheet. You could also use the extra 3 spare pins of the SPDT switch to toggle Composite Video IN off/on, but as this involved cutting the Video In cable, I decided not to do it; this means that you will not be able to have both signals connected at the same time (S-Video + Composite Video).
S-Video connector and toggle switch can be easily added to the rear part of the TV just by drilling two extra holes:
I've plugged Chroma+Luma signals from C64 and the colors look nice and crisp:
Inspired by S-video mod for Sony KV-9PT40 (Sanyo LA7672 Jungle)